Why is he doing this (sry so long)?

Well i wish i could tell you why he is doing this to you, but i have to say that getting away from him is exactly what you need to do, verbally abusive people are never fun to be around and just from what you said here, its pretty obvious that he doesn't deserve you. I'm sure you know all of this already but you need to also keep your son in mind. You don't want that kind of influence on anyone you care about. He sounds to me like he is desperate, and so he will do anything to get you back, even to the point of making you feel bad. My advice, Stay away.